This test assays aspects of locomotor, exploratory and emotional behavior (risk assessment and anxiety-like behavior) in response to a novel environment. The expected pattern of behavior is that animals will tend highly explore the novel arena initially, and eventually habituate to the open field [1, 2]. The test can be (and often is) repeated as long as due care is taken to ensure that both controls and treatment groups undergo all preceding procedures in an identical manner [3].

The open field has been extensively validated, ethologically and pharmacologically in both mice and rats [4-18]. Generally, females have higher activity levels than males, and young rodents have higher activity levels than old, but this can vary. The primary measures are locomotor activity (tracklength), exploration (number of rears), anxiety-like behavior (center activity and exploration) and risk assessment (stretched-attend postures. Adjunct measure (such as grooming, defecation, urination, ataxia, stereoptypies and compulsive behaviors) can also be assessed

1. Daenen, E.W.P.M., et al., Adaptation and habituation to an open field and responses to various stressful events in animals with neonatal lesions in the amygdala or ventral hippocampus. Brain Research, 2001. 918(1-2): p. 153.

6. Schmitt, U. and C. Hiemke, Combination of open field and elevated plus-maze: A suitable test battery to assess strain as well as treatment differences in rat behavior. Progress in Neuro-Psychopharmacology and Biological Psychiatry, 1998. 22(7): p. 1197.